The present invention relates to auxiliary power and more specifically to a method and apparatus for optionally adding a battery life extension device to a battery source of power.
Certain devices, such as cameras and the like, contain batteries that are constructed to meet specific requirements. The chemistry of different battery types is designed to deliver the type of power demanded for specific operations. Basically, alkaline batteries and to a lesser degree lithium-iron disulfide and nickel metal hydride batteries, which typically come in the AA size, are very sensitive to high current loads and pulses. In other words, when a load is very high current, or high drain, the battery may deliver the load, but at the cost of total energy output over the battery""s life. So, the general idea is to try to minimize high drains as much as possible to get more energy out of the batteries. Thus, for high current pulsed loads such as charging the strobe capacitor of a camera, batteries which are both high energy density and affected little in terms of capacity by high drains will provide the best battery performance. Thus, lithium metal primary batteries (lithium-manganese dioxide) are a typical choice for cameras (e.g., CR2, CR123, etc.) Digital cameras often use lithium ion rechargeable batteries for similar reasons.
Accordingly, film cameras typically come equipped with lithium batteries to maintain longer life, while digital cameras often favor lithium ion batteries for their small size and recharging ability. This presents a problem for a user when the battery is suddenly out of power in a location not convenient for the recharge or replacement of the proper battery which is some times hard to find. In such situations, it would be desirable for the user to be able to replace the lithium metal or lithium ion battery with an off the shelf AA battery having a traditional chemistry not particularly suited for instantaneously high energy demands.
When such AA batteries are used it would be further desirable for the camera, or other device using the battery, to have installed some mechanism for extending the life of the battery. Such mechanisms exist, for example in the form of a capacitor, which can be added to the electrical circuit to extend battery life. Such mechanisms are expensive and bulky and thus are not typically installed in a camera, except, perhaps, in some top of the line equipment.
Thus, it is desired to employ an electrical supply system which will accept batteries having different chemistries with systems that can operate to maximize the life of the battery type currently installed.
The present invention is directed to a system and method for a battery system adapter having a removable life extension device so that the entire system is not burdened with the size or weight of the device, or even the cost of the device, when the system is running with the proper high energy battery chemistry, such as a lithium ion battery.
Examples of a battery life extension devices are a capacitor, an ultra capacitor, or a super capacitor connected in parallel with the battery source. Such capacitance can add undesired cost and weight to a camera and typically would not be included with the camera. However, such a capacitor would improve battery life significantly when a user wishes to use standard AA batteries in the camera.
One embodiment of the invention provides for the optional use of a high capacitance ultra capacitor connectable across the AA batteries. This system then gives the user the flexibility to be able to buy batteries anywhere and yet have them perform better than they would otherwise in a system where a higher energy lithium ion battery is more appropriate.
In one embodiment, the battery system would include a battery carrier (sized for one or more AA batteries) which would be inserted into the camera (or other device that it is used in) and which would take the place of the lithium ion battery. The ultra capacitor would be optionally included in the battery carrier. The option to add the capacitor (or other life extending device) would reside with the user.
In an alternate embodiment, a separate slot could be constructed to optionally receive the capacitor.